MY 12 YEAR SON SUFFERS FROM MANY TYPES OF ALLERGIES AND ASTHMA. HE TAKES MEDICATION FOR BOTH. HE'S HAD ALL THE ALLERGY TESTING AND CAME UP ALLERGIC TO DOGS AND CATS. I WAS WONDERING IF HE WERE TO HAVE A DOG WOULD HIS ALLERGIES FLARE UP IMMEDIATELY OR WOULD IT TAKE SOME TIME?